Tianyi Cui
2ff112962b
Two round-3 findings: (A) The EOF-quiesce window reused the 3000ms SIGTERM grace, the SAME value as dsh-bash-local's own SIGTERM->SIGKILL grace. The child acp-agent's EOF teardown disposes its loop, which stops child-owned bash -- and a SIGTERM-trapping bash grandchild can hold that for up to ~3s before its own SIGKILL, then the child still owes a final flush. With both graces equal, the parent's SIGTERM fired exactly as the child reached its own SIGKILL+flush, cutting it off. Split the EOF grace into its own knob (disposeEofGraceMs, default 6000ms) that exceeds a single signal-grace of nested-teardown headroom. The child is an arbitrary ACP agent, so the value is a standalone generous default, NOT derived from any child's internals. Tier-1 test now uses a flush that outlasts the SIGTERM grace but fits the EOF grace, so it lands only because the EOF tier honors its own wider window (proven RED when tier 1 reuses the small SIGTERM grace). (B) The middle-tier (SIGTERM) test only asserted dispose returned in time, so an EOF->SIGKILL ladder with the rung removed would still pass. The mock's MOCK_IGNORE_EOF mode now installs a SIGTERM handler that touches an observable marker before exiting; SIGKILL is uncatchable, so removing the SIGTERM rung leaves the marker absent (proven RED). The test asserts the marker exists.
subagent/ — subagent capability family
The subagent seam: an agent delegating work to a child agent. Like the bash and llm families this is a capability seam (see capability seams) — but with one defining difference: multiple provider implementations coexist in one context, registered by name, rather than the single-implementation bash shape. The registry mirrors the LLM adapter registry.
| Package | Role | ctx key |
|---|---|---|
subagent/ |
Abstract subagent seam: named-provider registry + vocabulary | ctx.subagents |
subagent-spawn/ |
In-process backend: a fresh child agent (+ the shared run driver) | (registers on ctx.subagents) |
subagent-fork/ |
In-process backend: a child seeded with the parent's completed-turn prefix | (registers on ctx.subagents) |
subagent-acp/ |
Out-of-process backend: a child agent in a spawned subprocess, driven over ACP | (registers on ctx.subagents) |
tool-subagent/ |
Model-facing subagent delegation tool over ctx.subagents |
(registers on ctx.tools) |
The interface lives at subagent/subagent/. The in-process subagent-spawn / subagent-fork and the out-of-process subagent-acp backends ship here; the test-only dsh-subagent-mock (in support) is separate. All product packages except the mock.
The proposal and design rationale: docs/rfc/implemented/feature/2026-06-21-subagent-capability-seam.md.